AFRL Develops Additives to Improve Aircraft Engine Bearings

  • Published
  • By Materials & Manufacturing Directorate
  • AFRL/ML
WRIGHT-PATTERSON AIR FORCE BASE, Ohio --  AFRL fluids and lubricants experts managed three Small Business Innovation Research contracts to develop additives for the fully formulated gas turbine engine oils used with new aircraft engine bearings. These additives will improve the characteristics of the corrosion-resistant steel bearings to be used in engines of advanced aircraft such as the Joint Strike Fighter.

The development and testing of these additives involved collaboration among military and commercial institutions and showcased the technical expertise and leadership skills of AFRL's scientists and engineers. This research will provide a more suitable gas turbine engine oil for aircraft engines, which will aid in prolonging the life and enhancing the performance of advanced aircraft engines.

The Air Force operational environment requires aircraft to fly faster and carry more weight than currently qualified oils permit. Pursuing higher speeds and heavier loads results in increased temperatures and fatigue for aircraft engines. In addition, higher speeds and weight will require engines to produce more thrust, increasing the amount of stress typical for steel bearings in the engines. The new additives are totally soluble and react with iron surfaces to create the necessary lubrication, allowing engine bearings to be designed for maximum load-carrying capacity and minimum friction.

AFRL researchers received funding for three Phase I SBIR contracts. All three companies--METSS Corporation; UES, Inc.; and Wedeven Associates, Inc.--received tasking to develop and screen a number of additives for antiwear properties, as well as critical characteristics such as thermal stability and coking.

AFRL experts closely guided the effort, interfacing with the three SBIR companies; commercial oil companies NYCO S. A., ExxonMobil, AirBP, and Hatco; and engine companies Pratt & Whitney, General Electric, and Rolls Royce to open the lines of communication and information sharing among the involved parties. NYCO S. A. agreed to provide its oil for suitability testing and assessment with the additive candidates. 

The results of this effort demonstrate a ~2x improvement in wear using corrosion-resistant steel and candidate formulations compared to currently used steel with current gas turbine engine oils. Both Wedeven Associates and METSS Corporation subsequently received Phase II SBIR contracts.